Snow Leopard, channel exception errors and Path Finder

Posted by Pierre Igot in: Macintosh
September 4th, 2009 • 5:01 pm

There are new developments in the on-going saga of the channel exception errors.

Now that I have installed Snow Leopard, I haven’t been able to reproduce the problem on my Mac Pro, i.e. I haven’t experienced the permanent system-wide UI freeze that requires a hard reset or a remote shutdown. But it could just be a matter of time—although other people who experienced the problem much more frequently than me under Leopard report that, so far, they haven’t experienced the problem in Snow Leopard.

What I do experience since installing Snow Leopard, however, is a temporary freeze when Path Finder is running on my machine. When Path Finder is running, every once in a while (it happened to me twice within hours yesterday after installing Snow Leopard), the entire system freezes for up to 2 minutes, then comes back to normal as if nothing had happened.

There are no “channel exception error” messages in the system log, so I didn’t make the connection between the two then. But today I searched the Path Finder forums and sure enough, I found several posts by people reporting the same freeze, but at least some of those experiencing the freeze report also seeing “channel exception error” messages in the system log, along with temporary picture corruption, just like I used to experience in Preview under Leopard.

And what’s really interesting is that, in this thread on the Cocoatech forums, a Cocoatech staff member says this:

This is a known issue with OS X and NVIDIA GPUs. Path Finder makes use of the GPU with Core Animation, so that may be the trigger.

This problem existed before Snow Leopard, but I don’t know any solid details – I’d suggest contacting Apple. This thread on Apple support forum may shed some light on the issue.

He also adds, “You may want to mark ‘disable superfluous visual effects’ in the General tab of Path Finder’s preferences. It might avoid the OpenGL error.” However, some users report disabling that and still getting the freezes and display corruption.

And the Cocoatech employee also adds, after seeing a screen shot:

Yeah, that’s definitely an OpenGL error. I’m afraid there’s not much we can do about it until the NVIDIA drivers or hardware are fixed, the problem is much lower level than Path Finder.

This information confirms that the issue is known and that it needs to be fixed by those responsible for the NVIDIA drivers or hardware address it. I guess it’s not good news for Path Finder users like myself—although if it is a software issue there is hope that it will be fixed in a system update soon.

I am afraid we’ll have to continue to monitor the situation, and people running Path Finder on a Mac Pro like myself will have to do without it until the issue is properly addressed.

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